Savory Herb Tuna Casserole

Why This Savory Herb Tuna Casserole Works

During cooking, the butter, onion, and garlic coat the pan and slowly soften. The onion loses its bite and starts to taste sweeter, and the garlic mellows out. When the flour goes in, it sticks to the butter and forms a paste. As milk and chicken broth are whisked in, that paste swells and turns into a thick, smooth sauce that can actually cling to the noodles and tuna instead of running off.

Once the tuna, peas, and herbs are folded into that thick sauce, everything stays suspended and spread out. The noodles are already cooked, so in the oven they don’t need to cook more; they just soak up some of the sauce and stay tender instead of drying out. On top, the Parmesan melts and sticks to the crushed potato chips. With steady heat, the chips crisp up even more and the cheese sets, so the casserole comes out with a crunchy, salty lid over a creamy, soft center.

Mistakes To Avoid

Letting the flour, milk, and broth mixture stay thin and soupy before adding the tuna and noodles leaves the casserole watery. In the oven, the liquid doesn’t set into a creamy sauce, so the noodles float around and the topping never really sticks, giving a loose, soggy bake instead of slices that hold together.

Adding the tuna while the pan is still over the heat can dry it out. The fish keeps cooking in the hot sauce, so by the time the casserole comes out of the oven, the tuna turns tough and chalky instead of staying soft and flaky.

Overcooking the egg noodles on the stove makes them fall apart later. Once they bake in the sauce, the already-soft noodles swell, split, and turn mushy, so the whole dish becomes pasty instead of having separate, tender pieces.

Letting the potato chip topping sit too long before baking lets it soak up moisture from the sauce. In the oven it never crisps properly, so the top turns leathery and greasy instead of light and crunchy.